1. Field of the Invention
The present invention relates to network communications, and more particularly, to baseline wandering correction.
2. Description of the Prior Art
The phenomenon of baseline wandering at a receiver, in the context of Ethernet network communications or the like, has existed for a long time. It is a problem that those skilled in the art continue trying to resolve. Please refer to Taiwan Patent No. 497,334, Taiwan Patent No. 545,016, and U.S. Pat. No. 6,433,608 for related technology information on baseline wandering correction, the contents of all of which are incorporated herein by reference.
According to U.S. Pat. No. 6,433,608, if the goal of baseline wandering correction is to be achieved, certain conditions described by the following equations should be satisfied:
                    {                                                                                                  R                    o                                                        2                    ⁢                    L                                                  =                                  1                                                            R                      x                                        ⁢                    C                                                                                                                                            4                  ⁢                                      R                    ⁡                                          (                      gmx                      )                                                        ⁢                                      I                    c                                                  =                                  V                                      R                    x                                                                                                                                              (              1              )                                                                          (              2              )                                          
where definitions of related parameters and derivations of the equations have been disclosed and therefore can be found in U.S. Pat. No. 6,433,608. Detailed explanations are thus not repeated herein for brevity.
However, as the parameters L and Ro in equation (1) respectively represent an inductance value of a transformer and a resistance value of a matching resistor, and as the transformer and the matching resistor are stand-alone components, it is difficult to accurately control values of the parameters L and Ro, and especially the value of the parameter L. When the parameter L or the parameter Ro deviates from nominal value for any particular reason, such variation of manufacturing process or ambient temperature, the condition described by equation (1) becomes difficult to maintain, and therefore the baseline wandering phenomenon can not be effectively corrected.